; Sarcopenia, defined as loss of muscle mass and strength, affects as much as 70% of adults over the age of 60 years and is associated with significant functional decline, increased risk for injury, and decreased independence. Present literature suggests preferential loss of muscle fibers capable of generating high forces. We believe that motor control mechanisms are altered in older individuals, affecting their force generating ability. Motor control properties may be assessed through analysis of electromyographic signals. However, present clinical assessments for weakness can only measure the total torque generated about a joint by groups of muscles, and cannot provide valuable information regarding the torque exerted by a single muscle. Therefore, a critical need exists to develop tools that can measure the tension generated by individual muscles and accurately assess changes in strength and neuromotor drive. Intramuscular pressure (IMP) is the pressure produced within skeletal muscle as it changes length, and is a promising approach to gauge skeletal muscle function. Our long-term goal is to develop a minimally invasive clinical tool that can improve diagnostic and therapeutic strategies to improve the functioning of older individuals affected by weakness. This application's objectives are to develop and validate a minimally invasive method to assess neuromotor drive and force generation of individual muscles. Our central hypothesis is that simultaneous EMG and IMP measurements can be used to evaluate muscle electromechanical performance. To test this hypothesis, we will pursue two specific aims: AIM 1: Validate novel analyses of EMG and IMP measurements to evaluate electromechanical coupling in young adults. AIM 2: Evaluate sarcopenia-related changes in electromechanical coupling in older adults. The expected outcome of the proposed work is the development of an innovative methodology to evaluate the effect of aging and sarcopenia on the electromechanical performance of individual muscles. This work will be significant since it is the first step towards developing more effective tools for the assessment of muscle weakness, which, in turn, will improve diagnosis, monitoring of disease progression, and therapeutic strategies for elderly individuals struggling with the effects of sarcopenia.